*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
ul{

    list-style: none;
}

a{
    text-decoration: none;
}
html{
    font-size: 12px;
}
/* menu */
ul.menu{
    width: 100%;
    height: 35px;
    background: rgb(173, 171, 171);
}
ul.menu>li{
    position: relative;
    float: left;
}
ul.menu>li:nth-child(odd){
    width: 85px;
    height: 35px;
    border-top: 1px solid rgb(173, 171, 171);
    line-height:33px ;
    text-align: center;
}
ul.menu>li:nth-child(even){
    width: 1px;
    height: 11px;
    margin-top: 11px;
    background: #f00;
}
ul.menu>li:nth-child(odd) a{
    color: #000;
}
ul.menu>li:nth-child(odd):hover {
    background: #fff;
    border-top: 1px solid orangered;
    cursor: pointer;
}
/* 二级导航栏 */
ul.menu>li>ul{
    width: 0;
    height: 0;
    overflow: hidden;
    position: absolute;
    border: 1px solid #ccc;
    border-top: 0;
    background-color: #fff;
    top: 54px;
    opacity: 0;
}
ul.menu>li>ul>li{
    display: block;
    text-align: left;
    padding-left: 18px;
    height: 25px;
    line-height: 25px;
}
ul.menu>li:nth-child(3) a:hover{
    color: #f00;
}
ul.menu>li:nth-child(3):hover>ul{
    width: 153px;
    height: 139px;
    top: 34px;
    opacity: 1;
    transition: top .5s linear,opacity .5s linear;
}
ul.menu>li:nth-child(3)>ul>li{
    width: 120px;
}
ul.menu>li:nth-child(3)>ul>li:nth-child(4){
    height: 1px;
    margin: 6px 0;
    background: #eee;
}